Studies will continue to be directed at relations between structure and function in abnormal hemoglobins, and the mechanisms by which these hemoglobins may produce clinical disability. Particular emphasis will be placed on the effects of orally administered sodium cyanate on oxygen affinity, rate of red cell destruction, and clinical status, in patients with sickle cell anemia. Studies of the natural history of that disease, and screening programs for detection of electrophoretically "silent" hemoglobins with altered oxygen affinity or stability, continue.